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DESCRIPTION JP2012004655

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DESCRIPTION JP2012004655
An array speaker driving device and an acoustic system capable of efficiently supplying power to
a speaker with a small number of parts are provided. An array speaker driving device obtains an
average of instantaneous values of a plurality of input signals 1n to 8n corresponding to each of
a plurality of speakers 1s to 8s, and generates an average signal of the plurality of signals based
on the average. Adders 11c-17c, phase inverter 10 for inverting the phase of the average signal
generated by adders 11c-17c, amplifier 11 for amplifying the average signal whose phase is
inverted by phase inverter 10, and a plurality of inputs A plurality of adders 21c to 28c for
adding an average signal whose phase is inverted to each of the signals 1n to 8n and a plurality
of amplifiers 1a to 8a for amplifying a plurality of signals output from the plurality of adders 21c
to 28c . [Selected figure] Figure 2
Array speaker driving device and sound system
[0001]
The present invention relates to an array speaker driving device and an acoustic system for
driving an array speaker including a plurality of speakers.
[0002]
Humans grasp the acoustic space by the difference in the magnitude of the sound input to the
two ears or the time difference.
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A method of expressing a sound space with two speakers on the left and right using this matter,
that is, an acoustic system using stereo recording is generally used. In this acoustic system, a
method is used to make the sound pressure of the sound radiated from the left and right
speakers differ, and to make it appear as if the sound is coming from the position between the
two speakers, that is, panning. There is also a method of obtaining the same effect by utilizing the
time difference of reaching the microphone installed at a predetermined interval.
[0003]
However, the sound radiated from the left and right speakers is attenuated according to the
distance and the propagation time of those sounds is generated, so that the sound pressure
difference and time difference occur in the sound from the left and right speakers depending on
the position of the listener. . Therefore, the position where the panning effect as intended is
obtained is only on the central line equidistant from the two left and right installed speakers, and
the listener who is listening to the sound at other positions is closer to the listener It sounds as if
sound is emitted from the speaker in position. As a method for solving this problem, for example,
Non-Patent Document 1 describes an acoustic system that synthesizes the wave front of sound
using an array speaker by WFS (Wave Field Synthesis). WFS is a technology that synthesizes the
wave front of sound by superimposing the sound radiated from individual speakers using array
speakers arranged in one horizontal row, and causes the center point of the wave front of sound
to perceive the position of the sound source. Here, the central point of the wave front of the
sound generated from the array speaker is called a virtual sound source.
[0004]
FIG. 13 is an explanatory view showing a wavefront centered on the position of the virtual sound
source. In the figure, A1 indicates a virtual sound source, AL1 indicates the position of the virtual
sound source A1, and B1 to B3 indicate listeners. A stage and a listening seat are respectively
provided on both sides of the array speaker 4, a virtual sound source A1 is disposed on the stage,
and listeners B1 to B3 are disposed on the listening seat. According to WFS, the listeners B1 to
B3 perceive as if there is a sound source at the position of the virtual sound source A1 by
reproducing the wave front of the sound spreading from the virtual sound source A1 by the
speakers constituting the array speaker.
[0005]
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FIG. 14 is an explanatory view showing an example of the appearance of the array speaker. The
array speaker 4 is, for example, a horizontally long speaker installed on the floor on the stage
side from the vicinity of the boundary between the stage and the listening seat. The array
speaker 4 is composed of, for example, eight speakers 1s to 8s.
[0006]
In general, in WFS, a plurality of speakers constituting an array speaker can reproduce the wave
front to a high frequency sound if the installation interval of each speaker is short, and reproduce
the wave front of the sound if the installation width of the entire array speaker is long The
acoustic space that can be made can be expanded. Therefore, in WFS, excellent acoustic effects
can be obtained by using an array speaker composed of a large number of speakers. However,
since an amplifier for driving a speaker is provided for each speaker, an array speaker composed
of a large number of speakers requires the same number of amplifiers as the number of speakers,
which increases the cost of constructing an acoustic system.
[0007]
On the other hand, the configuration of an amplifier for driving a speaker is associated with a
power supply circuit for supplying a power supply voltage to the amplifier. In general, an
amplifier for driving a speaker applies a drive signal only to one input terminal of two input
terminals provided in the speaker, that is, a plus input terminal and a minus input terminal, and
the other input terminal receives a reference voltage, that is, ground. Take a method of
connecting (GND). As described above, a method of driving a speaker by connecting an amplifier
to only one input terminal of two input terminals of the speaker is referred to as a single driving
method. The single drive method includes a single power supply method having only a power
supply providing a high voltage to a reference voltage, and a dual power supply method having a
positive power supply providing a high voltage to the reference voltage and a negative power
supply providing a low voltage. There is.
[0008]
FIG. 15 is an explanatory view showing the configuration of an amplifier and an array speaker
using a single power supply system, and FIG. 16 is an explanatory view showing the
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configuration of an amplifier and an array speaker using a dual power supply system. In these
figures, 1 n to 8 n indicate input signals applied to the amplifiers 1 a to 8 a.
[0009]
In the case of the amplifiers 1a to 8a using the single power supply system shown in FIG. 15, the
outputs of the amplifiers 1a to 8a are often designed to operate around one half of the voltage of
the power supply 1p. For example, when the voltage of the power supply 1p is 12V, assuming
that the amplifier can output up to the power supply voltage amplitude, the outputs of the
amplifiers 1a to 8a operate with an amplitude of plus or minus 6V around the potential of 6V
and the speakers 1s to 8s To drive. However, as described above, the reference voltage is
connected to the input terminal on one side of the speakers 1s to 8s, and a potential difference of
6 V is generated between the reference voltage and the operation center voltage of the outputs of
the amplifiers 1a to 8a. Therefore, in order to prevent the DC voltage from being applied to the
speakers 1s to 8s, it is necessary to provide the DC blocking capacitors 1c to 8c between the
amplifiers 1a to 8a and the plus input terminals of the speakers 1s to 8s. In general, DC blocking
capacitors 1c to 8c need to have relatively large capacities, which increases the cost of
constructing an acoustic system. Furthermore, immediately after the power supply voltage is
applied to amplifiers 1a-8a, a charge current for storing DC blocking capacitors 1c-8c according
to the potential difference between the reference voltage and the operation center voltage flows.
It is necessary to take appropriate measures against the current, and if the measures are not
taken, an abnormal current flows in the speakers 1s to 8s, which causes so-called pop noise from
the speakers 1s to 8s, or in the worst case , Speakers 1s to 8s may be broken.
[0010]
In the case of the amplifiers 1a to 8a using the dual power supply system shown in FIG. 16, the
amplifiers are provided by providing two power supplies, a positive power supply 1p giving a
high voltage to the reference voltage and a negative power supply 2p giving a low voltage to the
reference voltage. It is possible to design 1a to 8a to operate around the reference voltage. For
example, when the power supply voltages of both power supplies are 12V, the outputs of the
amplifiers 1a to 8a operate with an amplitude of plus or minus 12V to drive the speakers 1s to
8s. In the case of the dual power supply system, since the above-described potential difference
does not occur, it is not necessary to provide the DC blocking capacitors 1c to 8c. However, in
the case of the dual power supply system, it is necessary to provide two power supplies, a
positive power supply 1p and a negative power supply 2p, and the cost increases significantly
depending on the configuration of the acoustic system. In particular, in order to construct an
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acoustic system for applying a DC voltage from the outside, the negative power supply 2p
requires a large-scale one using an inverter, which increases the cost.
[0011]
On the other hand, as a method for increasing the power supplied to the speakers constituting
the array speaker, there is a method for supplying driving signals of opposite phases to each
other to the plus input terminal and the minus input terminal of each speaker. It is called a drive
system. FIG. 17 is an explanatory view showing a configuration of an amplifier and an array
speaker using a bridge driving method. Here, 1 n to 8 n indicate input signals applied to the
amplifiers 1 a to 16 a.
[0012]
According to the bridge driving method, for example, when the voltage of the power supply 1p is
12 V, the outputs of the amplifiers 1a to 16a operate with an amplitude of plus or minus 12 V to
drive the speakers 1s to 8s, so the utilization efficiency of the power supply voltage is good. That
is, compared with a single drive system using a power supply having a potential difference of 12
V which supplies a drive signal only to the plus input terminals of the speakers 1s to 8s,
approximately four times as much power is supplied to the speakers 1s to 8s even with the same
power supply voltage. be able to. Further, since the speakers 1s to 8s are driven by the difference
between voltages output from the two amplifiers, there is no need to provide a DC blocking
capacitor even if the operation center voltages of the outputs of the two amplifiers are the same.
However, as shown in the figure, sixteen amplifiers 1a-16a and eight phase inverters 1r-8r are
required to drive the speakers 1s-8s, and the number of amplifiers is smaller than in the single
drive system. The cost is increased because the cost is doubled. As a method of solving this, for
example, Patent Document 1 describes an apparatus in which speakers are arranged in a grid
and these are time-division driven with a PWM (Pulse Width Modulation) signal to reduce the
number of amplifiers.
[0013]
Patent No. 4154601
[0014]
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Berghout, De Bries, D. de Vries, and P. Vogel, "Acoustic control by wave field synthesis"
(Netherlands), 93 (5) edition, Journal Of the Acoustical Society of America (J. Acoust.
Soc), May 1993, p. 2764-2778.
[0015]
However, in the device described in Patent Document 1, since the speakers arranged in a lattice
are driven in a time division manner, the time for driving each speaker decreases as the number
of speakers increases. That is, the power that can be supplied to each speaker decreases as the
number of speakers increases. Therefore, in order to supply sufficient power to each speaker, it is
necessary to increase the power supply voltage, which increases the cost including the selection
of various electronic components. Moreover, in order to drive a speaker by time division, the
operating frequency of an electronic component rises, so that the speaker to drive increases, for
that reason, while the electronic component which can operate at high speed is needed, many
unnecessary radiation generate | occur | produces. Because it is necessary, the cost is further
increased.
[0016]
The object of the present invention is made in view of the above-mentioned problem, and is to
provide an array speaker drive device and an acoustic system capable of efficiently supplying
power to a speaker with a small number of parts.
[0017]
The array speaker driving apparatus according to the present invention is an array speaker
driving apparatus for driving an array speaker including a plurality of speakers, wherein the
average value of the instantaneous values of a plurality of input signals corresponding to each of
the plurality of speakers is determined. Average signal generation means for generating an
average signal that becomes an average, phase inversion means for inverting the phase of the
average signal generated by the average signal generation means, and the phase inverted for
each of the plurality of input signals And means for adding the average signal.
[0018]
In the present invention, since the array speaker drive circuit is made common by using the high
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degree of similarity of input signals, it is possible to efficiently supply large power to the speaker
with respect to the power supply voltage with a small number of parts. An array speaker drive
circuit can be provided.
[0019]
The array speaker driving device according to the present invention further comprises amplitude
limiting means for limiting the amplitude of the average signal generated by the average signal
generating means to a predetermined value, and the phase inverting means is limited in
amplitude by the amplitude limiting means. The phase of the average signal is inverted.
[0020]
In the present invention, in order to impose amplitude limitation on the average signal, the input
signal has high similarity, and when the ratio of the average signal is large, the speaker
corresponding to the input signal is limited. It is possible to take out high output stably by
efficiently using the two systems of amplification units for driving the two powers provided in
the above.
[0021]
The array speaker driving device according to the present invention further comprises a low pass
filter for attenuating a signal corresponding to the average signal whose phase is inverted by the
phase inverting means from a predetermined frequency or more.
[0022]
According to the present invention, the terminals commonly connected to the terminals of the
speakers can be driven with low frequency components.
[0023]
The array speaker driving device according to the present invention comprises: amplifying means
for amplifying the amplitude of the average signal generated by the average signal generating
means by a factor of 2; and adding the average signal whose phase is inverted to the signal
output from the amplifying means And adding means.
[0024]
In the present invention, when the input signals have high similarity, the amplitude of the
average signal can be limited.
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[0025]
In the array speaker driving device of the present invention, the amplitude limiting means is a
soft clip circuit.
[0026]
In the present invention, by using the soft clipping circuit as the amplitude limiting means, the
occurrence of high frequency components can be reduced by not performing the steep amplitude
limitation, and it is possible to the input signal which is in phase with the large amplitude. Even
the sound system can be operated stably.
[0027]
The array speaker driving device according to the present invention is characterized by further
comprising a low pass filter for attenuating a predetermined frequency or more from a signal
corresponding to the signal outputted from the adding means.
[0028]
According to the present invention, a low frequency component signal can be efficiently output
to a speaker that is not included in the array speaker.
[0029]
An acoustic system according to the present invention corresponds to each of a plurality of
speakers in an acoustic system including an array speaker including a plurality of speakers each
having a first and a second input terminal and an array speaker driving device for driving the
array speaker. Means for calculating an average of instantaneous values of a plurality of input
signals, and generating an average signal whose amplitude becomes the average, and phase
inversion means for inverting the phase of the average signal generated by the average signal
generation means A first amplification means for amplifying an average signal whose phase is
inverted by the phase inversion means; a plurality of addition means for adding the average
signal whose phase is inverted to each of the plurality of input signals; And a plurality of second
amplification means for amplifying a plurality of signals output by a plurality of addition means,
wherein the signal output from the first amplification means is the plurality of The plurality of
signals supplied to the plurality of first input terminals of the power supply and output from the
plurality of second amplification means are respectively supplied to the plurality of second input
terminals of the plurality of speakers. It is characterized by
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[0030]
In the present invention, since the array speaker drive circuit is made common by using the high
degree of similarity of input signals, it is possible to efficiently supply large power to the speaker
with respect to the power supply voltage with a small number of parts. An acoustic system can
be provided.
[0031]
The sound system of the present invention is characterized by further comprising another
speaker, wherein a signal outputted from the first amplification means is given to the other
speaker.
[0032]
In the present invention, other speakers not included in the array speaker can emit sound.
[0033]
The acoustic system of the present invention is characterized by further comprising a low pass
filter for attenuating a predetermined frequency or more from the signal outputted from the first
amplification means.
[0034]
According to the present invention, other low frequency speakers not included in the array
speaker can emit sound.
[0035]
According to the present invention, power can be efficiently supplied to the speaker without
increasing the cost of the acoustic system due to the increase in the number of parts.
[0036]
It is a block diagram showing an example of composition of an acoustic system.
FIG. 2 is a block diagram showing an exemplary configuration of an amplification unit and an
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array speaker according to Embodiment 1;
It is explanatory drawing which shows typically an example of the arrangement | positioning
relationship of an array speaker and a virtual sound source.
FIG. 7 is a block diagram showing a configuration example of an amplifier and an array speaker
according to a second embodiment.
FIG. 7 is a block diagram showing an example of the configuration of an amplifier and an array
speaker according to a third embodiment.
It is a modification of a structure shown in FIG. 5, and is a block diagram which shows the
example of a structure which inserted the low pass filter between the amplifier and the speaker.
It is a modification of a structure shown in FIG. 5 or FIG. 6, and is a block diagram which shows
the example of a structure using one power supply.
It is a modification of the structure shown in FIG.5, FIG.6 or FIG. 7, and is a block diagram which
shows the example of a structure which carries out the bridge drive of the speaker by adding one
amplifier.
FIG. 13 is a block diagram showing an example of the configuration of an amplifier and an array
speaker according to a fourth embodiment.
FIG. 10 is a modification of the configuration shown in FIG. 9 and is a block diagram showing a
configuration example in which a low pass filter is inserted between an amplifier and a speaker.
It is a wave form diagram which shows typically the waveform of the signal of each part in the
structure shown in FIG.
FIG. 5 is a waveform chart schematically showing waveforms of signals of respective portions in
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the configuration shown in FIG. 4.
It is explanatory drawing which shows the wave front centering on the position of a virtual sound
source.
It is an explanatory view showing an example of appearance of an array speaker.
It is explanatory drawing which shows the amplifier and array speaker which used the single
power supply system.
It is explanatory drawing which shows the amplifier and array speaker which used both power
supply systems.
It is explanatory drawing which shows the structure of the amplifier using a bridge drive system,
and an array speaker.
[0037]
First Embodiment The first embodiment will be specifically described below with reference to the
drawings.
FIG. 1 is a block diagram showing an exemplary configuration of an acoustic system.
As shown in FIG. 1, the sound system includes m microphones 111 to 11 m, an amplification unit
1, a level adjustment unit 2, a signal processing unit 3, a control unit 6, a position information
holding unit 7, an operation unit 8, and an array speaker 4 Equipped with
In the present embodiment, the array speaker 4 is composed of, for example, eight speakers 1s to
8s.
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Also, m is an integer of 1 or more.
[0038]
The level adjustment unit 2 includes m level adjustment modules 21 to 2 m. The signal
processing unit 3 includes m × 8 delay units, variable gain amplifiers 311 to 3m8, and eight
adders 711 to 718. The operation unit 8 is an operation device for the operator to operate the
sound system, and includes a position information input unit 81 and a volume adjustment unit
82.
[0039]
The position information input unit 81 inputs position information including actual sound source
positions AL1 to AL4 that are positions of the performer input by the operator and positions of
the speakers 1s to 8s constituting the array speaker 4. The position information holding unit 7
gives the position information received from the operation unit 8 to the control unit 6.
[0040]
The volume control unit 82 gives amplification factors to each of the level control modules 21 to
2m according to the operation by the operator so that each audio signal is amplified to the
listening seat at an appropriate volume and volume balance. .
[0041]
The speakers 1s to 8s constituting the array speaker 4 emit a wave front of sound according to
the signal given from the amplification unit 1.
Details of the amplification unit 1 will be described later.
[0042]
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The level adjustment module 21 amplifies the audio signal input from the microphone 111, and
then supplies the amplified signal to the delay units and variable gain amplifiers 311 to 318 as a
first-system signal. The level adjustment module 22 amplifies the audio signal input from the
microphone 112, and then supplies the amplified signal to the delay units and variable gain
amplifiers 321 to 328 as a second system signal. The level adjustment module 2m amplifies the
audio signal input from the microphone 11m, and then supplies it to the delay unit and variable
gain amplifiers 3m1 to 3m8 as a signal of the mth system. Thus, each of the signals of the first to
m systems corresponding to the microphones 111 to 11 m is subjected to signal processing by
the delay unit and variable gain amplifiers 311 to 318, 321 to 328, ..., 3m1 to 3m8. Then, it is
separated into the signals of the first to eighth channels corresponding to the eight speakers 1s
to 8s, and is supplied to the amplification unit 1.
[0043]
The delayer and variable gain amplifiers 311 to 318 delay the signal of the first system and
perform variable gain amplification. Also, the delayer and variable gain amplifiers 321 to 328
delay the signal of the second system and perform variable gain amplification. The delayer and
variable gain amplifiers 3m1 to 3m8 delay the signal of the m-th system and perform variable
gain amplification. As described above, the delay unit and variable gain amplifiers 311 to 318,
321 to 328, ..., 3m1 to 3m8 respectively delay the signals of the first to m systems and perform
variable gain amplification, but the delay amount thereof The amplification factor is calculated by
the control unit 6. That is, the delay unit and variable gain amplifiers 311 to 318, 321 to 328, ...,
3m1 to 3m8 individually separate the signals of the first system to the mth system according to
the delay amount and amplification factor calculated by the control unit 6. Delay and amplify
variable gain.
[0044]
The adder 711 adds the output signals of the delay unit and the variable gain amplifiers 311 to
3m1 and supplies the result to the amplification unit 1 as a signal of the first channel. The adder
712 adds the output signals of the delay and variable gain amplifiers 312 to 3 m 2 and supplies
the result to the amplification unit 1 as a signal of the second channel. The adder 718 adds the
output signals of the delay and variable gain amplifiers 318 to 3m 8 and supplies the result to
the amplification unit 1 as a signal of the eighth channel. Thus, the signal processing unit 3
applies the signals of the first to eighth channels to the amplification unit 1. The amplification
unit 1 amplifies the input first to eighth channel signals and supplies the amplified signals to
eight speakers 1 s to 8 s constituting the array speaker 4. Then, the speakers 1s to 8s emit a
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wave front of sound based on the signal supplied from the amplification unit 1.
[0045]
FIG. 2 is a block diagram showing a configuration example of an amplification unit and an array
speaker according to the first embodiment. That is, FIG. 2 shows an amplifying unit 1 for
amplifying a signal supplied from the signal processing unit 3 in FIG. 1 and an array speaker 4
for emitting a wave front of sound according to the signal supplied from the amplifying unit 1.
[0046]
The input signals 1n to 8n are signals provided from the signal processing unit 3 to the
amplification unit 1, and the signals correspond to the signals provided to the speakers 1s to 8s
by the amplification unit 1. The amplification unit 1 includes adders 11 c to 17 c, a phase
inverter 10, adders 21 c to 28 c, an amplifier 11 and amplifiers 1 a to 8 a. The adders 11c to 17c
add the input signals 1n to 8n. The value of the added signal is divided by 8, and the signal
representing the average of the instantaneous values of the input signals 1 n to 8 n (hereinafter
referred to as the common signal 5). ) Is obtained. The phase inverter 10 inverts the phase of the
common signal 5 and supplies it to the amplifier 11 and the adders 21c to 28c. The adders 21 c
to 28 c add the input signals 1 n to 8 n to the common signal 5 phase-inverted by the phase
inverter 10. That is, in the adders 21c to 28c, the common signals 5 are subtracted from the
input signals 1n to 8n, and the subtraction results are given to the amplifiers 1a to 8a,
respectively. The amplifier 11 amplifies the common signal 5 phase-inverted by the phase
inverter 10 and supplies the common signal 5 to the common electrodes of the speakers 1s to 8s.
The common electrode is one in which electrodes (minus input terminals) not connected to the
amplifiers 1a-8a among the drive electrodes of the speakers 1s-8s are collectively treated as one
circuit end. That is, in the present embodiment, since the common signal 5 is amplified by the
single amplifier 11 and supplied to the negative input terminal of each of the speakers 1s to 8s
by the common wiring, a signal supplied to the negative input terminal of each of the speakers 1s
to 8s The voltages on the On the other hand, the amplifiers 1a-8a amplify the signals obtained by
subtracting the common signal 5 from the input signals 1n-8n by the adders 21c-28c, and are
connected to the amplifiers 1a-8a among the drive electrodes of the speakers 1s-8s. The eight
speakers 1s to 8s are individually driven by applying them to the electrodes (plus input
terminals). Since each of the speakers 1s to 8s is connected to the amplifiers 1a to 8a and the
amplifier 11, the difference signal between the output signal of the amplifiers 1a to 8a and the
output signal of the amplifier 11 is input to each of the speakers 1s to 8s. become. As a result,
from each of the speakers 1s to 8s, input signals 1n to 8n corresponding to the respective
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speakers 1s to 8s are amplified and emitted.
[0047]
WFS is a method aiming at generating some wave front by superimposing sound waves radiated
from a plurality of speakers 1s to 8s constituting the array speaker 4. Therefore, the respective
signals given from the amplification unit 1 to the speakers 1s to 8s have high similarity to one
another. In WFS, for example, a wavefront centered on the virtual sound source A1 is obtained by
determining the delay and distance attenuation when the sound wave propagates from the virtual
sound source A1 to the speakers 1s to 8s using the delay unit and variable gain amplifier 318 to
3m8. It radiates from the array speaker 4.
[0048]
As described with reference to FIG. 13, by radiating from the array speaker 4 a wave front of
sound spreading from the position AL1 of the virtual sound source A1, whether listeners B1 to
B3 have a sound source at the position AL1 of the virtual sound source A1 To perceive like. At
this time, in FIG. 1, the position information holding unit 7 calculates the distance between the
virtual sound source A1 and the speakers 1s to 8s constituting the array speaker 4 with respect
to the input of the audio signal corresponding to the virtual sound source A1 and controls Give
the part 6 that distance. The control unit 6 calculates the delay amount and the amplification
factor based on the distance. Next, the control unit 6 sets the delay amount and amplification
factor in the delay units and variable gain amplifiers 318 to 3m8 provided corresponding to the
speakers 1s to 8s, respectively. Assuming that the delay amount set in the delay unit is td, the
amplification factor set in the variable gain amplifier is G, and the distance between the virtual
sound source and each of the speakers 1s to 8s is d, the delay amount td, amplification factor G
and distance d can be obtained by the following equation. Delay amount td = d / cc is the speed
of sound amplification factor G = d <r> r is the distance attenuation constant (0> r> −2) Thus,
the signal processing unit 3 receives an input corresponding to the virtual sound source A1. The
delay amount and amplification factor are set for the received signal, and the delay unit and the
amplified signal are applied to the amplification unit 1.
[0049]
The signal supplied from the signal processing unit 3 to the amplification unit 1 has a time
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difference determined depending on the relative difference in distance between the virtual sound
source A1 and the speakers 1s to 8s constituting the array speaker 4, and further, the virtual
sound source A1 and each speaker The level is determined depending on the distance of 1s to 8s.
Therefore, when the distance between each of the speakers 1s to 8s constituting the array
speaker 4 is shorter than the wavelength of sound, or when the distance between the array
speaker 4 and the virtual sound source A1 is long, it is given to each amplifier in the
amplification unit 1 The phase difference of the signals is reduced. On the other hand, when the
width of the array speaker 4 is shorter than the wavelength, or when the angle between the array
speaker 4 and the virtual sound source A1 is close to a right angle, the maximum value of the
phase difference of the signals applied to each amplifier in the amplification unit 1 Becomes
smaller.
[0050]
That is, when outputting a wavefront having a large curvature toward the front direction of the
array speaker 4, and when the wavelength of sound radiated in the front direction of the array
speaker 4 is sufficiently long compared to the width of the array speaker 4, the array speaker
The signals given to the speakers 1s to 8s constituting 4 include a large common component, and
the similarity of the signals is high. In a general use state, the signal input to the array speaker 4
contains many components that satisfy the above conditions, so the signal to which the amplifier
11 shown in FIG. 2 contributes is increased and is applied to each of the speakers 1s to 8s. Signal
components are distributed to the amplifiers 1a to 8a and the amplifier 11. By this, even with the
same power supply voltage, it is possible to apply at most twice the voltage as compared with the
case of the single drive described above, and it is possible to increase the utilization efficiency of
the power supply voltage. In particular, low frequency sound is generally recorded at a higher
signal level than high frequency sound, and in general, low frequency speakers are generally
more efficient than high frequency speakers. Although it is effective to increase the power supply
capability of low frequency signals to increase the output of the acoustic system, low frequency
signals are easily extracted as a common component of the input signal because the wavelength
is long, and this embodiment is effective. It turns out that it works. This will be described in more
detail using the drawings.
[0051]
FIG. 3 is an explanatory view schematically showing an example of an arrangement relationship
between an array speaker and a virtual sound source. In FIG. 3, the array speaker 4 is composed
of speakers 1s to 8s. In addition, a virtual sound source A1 is disposed on the back side of the
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speakers 1s to 8s. The speakers 1s to 8s constituting the array speaker 4 are installed at
intervals of 20 cm. The virtual sound source emits a sine wave of 100 Hz and is disposed on the
back side 50 cm away from the front of the array speaker 4 and 5 cm away from the center of
the array speaker 4.
[0052]
FIG. 11 is a waveform chart schematically showing waveforms of signals of respective portions in
the configuration shown in FIG. Here, the horizontal direction of the waveform indicates time,
and the vertical direction indicates amplitude or voltage. FIG. 11A shows waveforms of input
signals 1n, 2n, 4n among the input signals 1n-8n given from the signal processing unit 3 to the
amplification unit 1 in the arrangement shown in FIG. In actual waveforms, the input signals 1 n
to 8 n appear as a bundle of highly similar waveforms, but here only the input signals 1 n, 2 n
and 4 n are shown as an example. FIG. 11B shows the waveform of the common signal 5
obtained from the adders 11c, 12c and 14c. FIG. 11C shows the waveforms of the output signals
11a, 22a, 44a of the amplifiers 1a, 2a, 4a and the output signal 5b of the amplifier 11. FIG. 11D
shows waveforms of voltages applied to the speakers 1s, 2s and 4s. From these figures, it can be
seen that in an actual acoustic system that reproduces a wavefront using the array speaker 4,
each input signal has high similarity, and the acoustic system based on the present embodiment
operates effectively.
[0053]
In the present embodiment, since the speakers 1s to 8s are driven by the difference between the
output signals of the amplifiers 1a to 8a and the output signal of the amplifier 11, the central
voltages of the operations of the amplifiers 1a to 8a should be made common. There is no need
to insert a DC blocking capacitor even if the acoustic system is configured with a single power
supply.
[0054]
Further, in the present embodiment, since the amplifiers are shared by utilizing the similarity of
the input signals 1n to 8n, the number of amplifiers and the number of wirings are reduced by
about half as compared with the above-described bridge drive circuit. Can.
When n speakers are driven by the bridge drive circuit, the number of amplifiers is 2n and the
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number of wires is 2n. According to the present embodiment, the number of amplifiers is n + 1
and the number of wires is n + 1. I need only a book. At this time, since the number of amplifiers
is reduced to about half, it is possible to reduce the power consumption of the amplifiers which is
consumed even during no load.
[0055]
Further, in the present embodiment, since the common signal 5 is amplified by the single
amplifier 11 and is applied to the speakers 1s to 8s by the common wiring, the voltages of the
common signal 5 applied to the speakers 1s to 8s are equal. As compared with the case where
the speakers 1s to 8s are driven by respective amplifiers, variations in the applied voltage due to
the common signal 5 due to an amplification factor error of the amplifiers can be avoided. If the
extraction of the common signal 5 and the subtraction from each signal component are
performed by digital processing, an error in the subtraction unit does not occur in principle, and
a variation on the common signal 5 does not occur in principle.
[0056]
Furthermore, in the present embodiment, with respect to the output currents of the amplifiers 1a
to 8a connected to the respective speakers 1s to 8s, the output currents of the amplifiers 1a to
8a giving the common signal 5 have all input signals in phase. There is a maximum in some
cases, which is a multiple of the number of speakers 1s to 8s. Therefore, if the output current
capacity of the amplifier 11 giving the common signal 5 is an integral multiple of the number of
speakers 1s to 8s of the output current capacities of the amplifiers 1a to 8a connected to the
speakers 1s to 8s, the current The sound system can be configured without loss of capacity.
[0057]
In FIG. 2, although subtraction is realized by adding the inversion of the common signal 5 to each
of the input signals 1n to 8n, a subtractor is inserted in each of the input signals 1n to 8n and the
common signal 5 is subtracted. Is equivalent to Further, the extraction of the common signal 5
and the subtraction processing from each signal may be performed by digital processing using a
DSP (Digital Signal Processor) or the like, or may be performed by analog processing. Similarly,
the amplifiers 1a-8a driving the respective speakers 1s-8s may be either analog operation or
switching operation.
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[0058]
Second Embodiment The second embodiment will be specifically described below with reference
to the drawings. The configuration of the sound system is substantially the same as the
configuration shown in FIG. FIG. 4 is a block diagram showing a configuration example of an
amplifier and an array speaker according to a second embodiment. That is, FIG. 4 shows an
amplification unit 1 that receives a signal from the signal processing unit 3 in FIG. 1 and an array
speaker 4 that receives a signal from the amplification unit 1.
[0059]
The input signals 1n to 8n are signals provided from the signal processing unit 3 to the
amplification unit 1, and the signals correspond to the signals provided to the speakers 1s to 8s
by the amplification unit 1. The amplification unit 1 includes adders 11c to 17c, a phase inverter
10, an amplitude limiter 12, adders 21c to 28c, an amplifier 11 and amplifiers 1a to 8a. The
present embodiment differs from the first embodiment in that the amplitude limiter 12 is
provided. The adders 11c to 17c add the input signals 1n to 8n. The value of the summed signal
is divided by 8 to obtain a common signal 5 representing the mean of the instantaneous values of
the input signals 1 n to 8 n. The amplitude limiter 12 performs amplitude limitation on the
common signal 5 obtained by the adders 11 c to 17 c, and applies the amplitude limited signal
50 a to the phase inverter 10. The phase inverter 10 inverts the phase of the signal 50a and
supplies it to the amplifier 11 and the adders 21c to 28c. The adders 21 c to 28 c add the input
signals 1 n to 8 n to the signal 50 a phase-inverted by the phase inverter 10. That is, in the
adders 21c to 28c, subtraction of the signal 50a from the input signals 1n to 8n is performed,
and the subtraction results are given to the amplifiers 1a to 8a, respectively.
[0060]
The amplifier 11 amplifies the signal 50a phase-inverted by the phase inverter 10, and supplies
the amplified signal 50a to the common electrodes of the speakers 1s-8s. The common electrode
is one in which electrodes (minus input terminals) not connected to the amplifiers 1a-8a among
the drive electrodes of the speakers 1s-8s are collectively treated as one circuit end. That is, in
the present embodiment, the signal 50a is amplified by the single amplifier 11 and is applied to
the negative input terminal of each of the speakers 1s to 8s by the common wiring, so that the
11-04-2019
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signal 50a is supplied to the negative input terminals of each of the speakers 1s to 8s. The
voltages are equal. On the other hand, the amplifiers 1a-8a amplify the signals obtained by
subtracting the signal 50a from the input signals 1n-8n by the adders 21c-28c, and among the
drive electrodes of the speakers 1s-8s, the electrodes connected to the amplifiers 1a-8a The eight
speakers 1s to 8s are individually driven by outputting them to (plus input terminals). Since each
of the speakers 1s to 8s is connected to the amplifiers 1a to 8a and the amplifier 11, the
difference signal between the output signal of the amplifiers 1a to 8a and the output signal of the
amplifier 11 is input to each of the speakers 1s to 8s. become. As a result, from each of the
speakers 1s to 8s, input signals 1n to 8n corresponding to the respective speakers 1s to 8s are
amplified and emitted.
[0061]
As in the first embodiment, the signals input to the speakers 1s to 8s constituting the array
speaker 4 include large common components, and the similarity between the signals is high. In a
general use state, the signal input to the array speaker 4 contains many components that satisfy
the above conditions, so the number of signals contributed by the amplifier 11 shown in FIG. 4
increases. In particular, the phases of the input signals 1n to 8n If the signal is concentrated, the
signal concentrates on the amplifier 11. As a result, if the maximum output level of the amplifier
11 is exceeded, there is a risk that a sufficient output voltage can not be secured. Therefore, the
above phenomenon can be prevented by providing the amplitude limiter 12 and limiting the
amplitude of the signal 50a to a voltage corresponding to the maximum output level of the
amplifier 11.
[0062]
FIG. 12 is a waveform diagram schematically showing waveforms of signals of respective
portions in the configuration shown in FIG. In the figure, the horizontal direction of the waveform
corresponds to the time direction, and the vertical direction of the waveform corresponds to the
amplitude of the waveform. FIG. 12A shows waveforms of the input signals 1n, 2n, 4n among the
input signals 1n-8n given from the signal processing unit 3 to the amplification unit 1 in the
arrangement shown in FIG. In actual waveforms, the input signals 1 n to 8 n appear as a bundle
of highly similar waveforms, but here only the input signals 1 n, 2 n and 4 n are shown as an
example. FIG. 12B shows the waveforms of the common signal 5 and the signal 50a obtained
from the adders 11c, 12c and 14c. FIG. 12C shows the waveforms of the output signals 11a, 22a,
44a of the amplifiers 1a, 2a, 4a and the output signal 10a of the amplifier 11. FIG. 12D shows
waveforms of voltages applied to the speakers 1s, 2s and 4s. From these figures, it can be seen
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that the acoustic system according to the present embodiment operates effectively even if the
amplitude of the common signal 5 exceeds the maximum output level of the amplifier 11.
[0063]
As described above, the amplitude limiter 12 limits the amplitude of the common signal 5 to a
voltage corresponding to the maximum output level of the amplifier 11, but if the amplitude
limiter 12 sharply limits the amplitude, the amplifiers 1a to 8a and A high frequency component
is generated in the output signal of the amplifier 11, and noise may be added to the drive signals
of the speakers 1s to 8s. At this time, the operation of the amplitude limiter 12 is a soft clip type,
and the steep amplitude limitation is not performed, so that the generation of high frequency
components can be reduced, and for the input signals 1n to 8n which are in phase with large
amplitude. Even the sound system can be operated stably.
[0064]
Third Embodiment The third embodiment will be specifically described below with reference to
the drawings. The configuration of the sound system is substantially the same as the
configuration shown in FIG. FIG. 5 is a block diagram showing a configuration example of an
amplifier and an array speaker according to the third embodiment. That is, FIG. 5 shows an
amplification unit 1 for inputting a signal from the signal processing unit 3 in FIG. 1, an array
speaker 4 for inputting a signal from the amplification unit 1, and a bass speaker 9 s. Here, the
bass speaker 9 s is not included in the array speaker 4. The present embodiment is different from
the first embodiment in that the bass speaker 9s is provided separately from the array speaker 4.
The input signals 1n to 8n are signals provided from the signal processing unit 3 to the
amplification unit 1, and the signals correspond to the signals provided to the speakers 1s to 8s
by the amplification unit 1. The amplification unit 1 includes adders 11 c to 17 c, a phase
inverter 10, adders 21 c to 28 c, an amplifier 11 and amplifiers 1 a to 8 a. The adders 11c to 17c
add the input signals 1n to 8n. The value of the added signal is divided by 8, and the signal
representing the average of the instantaneous values of the input signals 1 n to 8 n (hereinafter
referred to as the common signal 5). ) Is obtained. The phase inverter 10 inverts the phase of the
common signal 5 and supplies it to the amplifier 11 and the adders 21c to 28c. The adders 21 c
to 28 c add the input signals 1 n to 8 n to the common signal 5 phase-inverted by the phase
inverter 10. That is, in the adders 21c to 28c, the common signals 5 are subtracted from the
input signals 1n to 8n, and the subtraction results are given to the amplifiers 1a to 8a,
respectively.
11-04-2019
21
[0065]
The amplifier 11 amplifies the common signal 5 phase-inverted by the phase inverter 10 and
supplies the common signal 5 to the common electrodes of the speakers 1s to 8s. The common
electrode is one in which electrodes (minus input terminals) not connected to the amplifiers 1a8a among the drive electrodes of the speakers 1s-8s are collectively treated as one circuit end.
That is, in the present embodiment, since the common signal 5 is amplified by the single
amplifier 11 and supplied to the negative input terminal of each of the speakers 1s to 8s by the
common wiring, a signal supplied to the negative input terminal of each of the speakers 1s to 8s
The voltages on the On the other hand, the amplifiers 1a-8a amplify the signals obtained by
subtracting the common signal 5 from the input signals 1n-8n by the adders 21c-28c, and are
connected to the amplifiers 1a-8a among the drive electrodes of the speakers 1s-8s. The eight
speakers 1s to 8s are individually driven by applying them to electrodes on one side (plus input
terminal).
[0066]
Since each of the speakers 1s to 8s is connected to the amplifiers 1a to 8a and the amplifier 11,
the difference signal between the output signal of the amplifiers 1a to 8a and the output signal of
the amplifier 11 is input to each of the speakers 1s to 8s. become. As a result, from each of the
speakers 1s to 8s, input signals 1n to 8n corresponding to the respective speakers 1s to 8s are
amplified and emitted.
[0067]
On the other hand, the bass speaker 9s not included in the array speaker 4 is connected to the
amplifier 11 and the reference voltage. As a result, the bass speaker 9s is driven according to the
common signal 5 of the input signals 1n to 8n. Here, as described above, the common signal 5 of
the input signals 1 n to 8 n includes many low frequency components. Therefore, it is effective to
drive the bass speaker 9s using the common signal 5. In general, the array speaker 4 is often
composed of a speaker with a relatively small aperture, but it is therefore difficult to reproduce
sufficient bass. Therefore, by providing the bass speaker 9s separately from the array speaker 4,
the broadband of the sound system can be achieved. Further, in the present embodiment, the
bass speaker 9s can be added to the sound system without the addition of an amplifier. Although
the output signal of the amplifier 11 is directly connected to the bass speaker 9s in the
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configuration shown in FIG. 5, a low pass filter may be inserted between the amplifier 11 and the
bass speaker 9s.
[0068]
FIG. 6 is a modification of the configuration shown in FIG. 5 and is a block diagram showing a
configuration example in which a low pass filter is inserted between the amplifier and the
speaker. As can be seen from the figure, a low pass filter 13 is provided between the amplifier 11
and the bass speaker 9s. By providing the low pass filter 13, a signal from which high frequency
components have been removed can be given to the bass speaker 9s. Further, although the sound
system is configured using both power supplies in the configuration shown in FIG. 5 and FIG. 6,
the sound system may be configured using a single power supply.
[0069]
FIG. 7 is a modification of the configuration shown in FIG. 5 or 6 and is a block diagram showing
a configuration example using a single power supply. As can be seen from the figure, a DC
blocking capacitor 14 is provided between the low pass filter 13 and the speakers 1s to 8s. By
providing the DC blocking capacitor 14, it is possible to prevent the DC voltage from being
applied to the bass speaker 9s. In the configurations shown in FIG. 5, FIG. 6 and FIG. 7, the
speakers 1s to 8s are driven in a single manner, but one amplifier may be added to bridgely drive
the speakers 1s to 8s.
[0070]
FIG. 8 is a modification of the configuration shown in FIG. 5, FIG. 6 or FIG. 7 and is a block
diagram showing a configuration example in which one amplifier is added to bridge drive a
speaker. As can be seen from the figure, an amplifier 9a is provided in addition to the amplifiers
1a to 8a.
[0071]
Fourth Embodiment The fourth embodiment will be specifically described below with reference
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to the drawings. The configuration of the sound system is substantially the same as the
configuration shown in FIG. FIG. 9 is a block diagram showing a configuration example of an
amplifier and an array speaker according to the fourth embodiment. That is, FIG. 9 shows an
amplification unit 1 for inputting a signal from the signal processing unit 3 in FIG. 1, an array
speaker 4 for inputting a signal from the amplification unit 1, and a bass speaker 9s. Here, the
bass speaker 9 s is not included in the array speaker 4. The input signals 1n to 8n are signals
provided from the signal processing unit 3 to the amplification unit 1, and the signals correspond
to the signals provided to the speakers 1s to 8s by the amplification unit 1. The amplification unit
1 includes adders 11 c to 17 c, a phase inverter 10, an amplitude limiter 12, adders 21 c to 28 c,
an amplifier 11, amplifiers 1 a to 8 a, and an amplifier 16. The adders 11c to 17c add the input
signals 1n to 8n. The value of the added signal is divided by 8 to obtain the common signal 5 of
the input signals 1 n to 8 n. The amplitude limiter 12 performs amplitude limitation on the
average of the input signals obtained by the adders 11 c to 17 c, and applies the amplitude
limited signal 50 a to the phase inverter 10. The phase inverter 10 inverts the phase of the signal
50a and supplies it to the amplifier 11, the amplifiers 1a to 9a and the adders 21c to 28c. The
adders 21 c to 28 c add the input signals 1 n to 8 n to the signal 50 a phase-inverted by the
phase inverter 10. That is, in the adders 21c to 28c, subtraction of the signal 50a from the input
signals 1n to 8n is performed, and the subtraction results are given to the amplifiers 1a to 8a,
respectively. The amplifiers 1a to 8a amplify the signals output from the adders 21c to 28c, that
is, the signals obtained by subtracting the signal 50a from the input signals 1n to 8n, and apply
the amplified signals to one electrode (plus input terminal) of the speakers 1s to 8s.
[0072]
On the other hand, the amplifier 9a outputs the signal 50a from the signal 5 doubled by the
amplifier 16 by the adder 29c to drive the bass speaker 9s. Although the output signal of the
amplifier 11 is directly connected to the bass speaker 9s in the configuration shown in FIG. 9, a
low pass filter may be inserted between the amplifier 11 and the bass speaker 9s.
[0073]
FIG. 10 is a modification of the configuration shown in FIG. 9 and is a block diagram showing a
configuration example in which a low pass filter is inserted between the amplifier and the
speaker. As can be seen from the figure, a low pass filter 13 is provided between the amplifier 11
and the bass speaker 9s. By providing the low pass filter 13, a signal from which high frequency
components have been removed can be given to the bass speaker 9s.
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[0074]
Modifications The present invention is not limited to the above-described embodiment, and can
be implemented in other aspects. Several aspects are shown as a modification below. In the
embodiment described above, although the number of main units constituting the sound system
is expressed as eight, the sound system can be configured with any number of main units. In
addition, when the average of the instantaneous values of the input signals 1 n to 8 n is obtained,
it is realized by addition of the output of one adder and the input signal, that is, an adder adding
two signals. An adder capable of addition may be used. Further, the number of speakers not
included in the array speaker 4 is not limited to one, and can be realized by an arbitrary number.
In this case, speakers not included in the array speaker 4 may be connected in parallel or in
series. The number of main units constituting the sound system is eight, and the amplifiers 1a to
8a commonly driving the eight speakers 1s to 8s are provided, but the number of main units
constituting the sound system is If so, the sound system may be divided into multiple groups.
Although the speaker not included in the array speaker 4 is added, the speaker not included in
the array speaker 4 may be the same housing as the array speaker 4 or a separate housing.
Moreover, although the adder, the subtraction part, and the amplitude limiting part were
provided in the acoustic system, you may integrate the function into an amplifier, for example.
Moreover, although the speakers 1s-8s which comprise the array speaker 4 are expressed as an
individual component, a housing | casing and a diaphragm may be common. That is, the
component represented as a speaker may be a component that performs electro-mechanical
conversion in the electroacoustic transducer. Further, as a signal processing method for driving
the speaker array, a signal processing method other than WFS may be used.
[0075]
Reference Signs List 1 amplification unit 2 level adjustment unit 3 signal processing unit 4 array
speaker 6 control unit 7 position information holding unit 8 operation unit 1s to 8s speaker 9s
bass speaker 1n to 8n input signal 11c to 17c adder 21c to 28c adder 10 phase Invertor 11, 1a
to 9a, 16 amplifier A1 virtual sound source 12 amplitude limiter 13 low pass filter 1c to 8c
capacitor 1p, 2p power supply
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